Voice-transmitting gas mask



Nov. 5, 1946. A. V. MOT$|NGER 2,

VOICE-TRANSMITTING GAS MASK v I Filed May 17, 1938 ,3 Sheet-Sheet 1 INVEN TOR.

' Armand VMotsiny BY Y A ATTORNEY 1946. A. v. MOT SINGERVOICE-TRANSMITTING GAS MASK I Filed May 17, 1958 V 3 Sheets-Sheet 2INVENTOR. Armand VMotgi n A TTORNEY Nqv. 5, .1946; A. v; MOTSINGERVOICE-TRANSMITTING GAS MASK 5 Sheets-Sheet 3 Filed May 17, 1938 FIG. .91-76. /0

IN V EN TOR. A rm and. V- Motsinyer M A TTORNEY Patented Nov. 5, 1946UNITED STATES PATENT OFFICE VOICE-TRANSMITTING GAS MASK Armand V.Motsinger, near Aberdeen, Md. Application May 17, 1938, Serial No.208,408

12 Claims. (01. 128-141) (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) The invention described hereinmay be manufactured and used by and for the Government for governmentalpurposes, without the payment to I me of any royalty thereon.

This invention relates to voice-transmitting gas masks and has for anobject to provide a gas mask through which a person can talk without theuse of electrical or other outside energy.

Another object of this invention is to provide a diaphragm which willreadily transmit the human voice.

Another object of this invention is to provide a sound box or acousticalchamber next to a diaphragm in order to increase the transmission ofspeech through the diaphragm.

Another object of this invention is to provide a sound box or acousticalchamber that is adjustable so as to conform to the individual voice ofthe wearer of a mask or to the sound characteristics of a given mask.

Another object of this invention is to provide a facepiece of a gas maskwith diaphragms and acoustical chambers on either side of the facepiecewhich may respond to different sound frequencies.

With the foregoing and other objects in view, the invention consists incertain novel features of construction and arrangement of parts as willbe more fully disclosed in connection with the accompanying drawings.

In the drawings:

Fig.1 is a sectional view on line I-l of Fig. 2 of a facepiece of a gasmask in place on the face, showing th position of the acoustical chamberand diaphragm.

Fig. 2 is a front view of a facepiece, in place on a mans head, showingthe diaphragm in the front part of the facepiece.

Fig. 8 is a front view of a facepiece, in place on a mans head, showingangletubes with diaphragms on the side of the facepiece.

Fig. 4 is a front view of an angletube of a facepiece showing deflectorsin the acoustical chamber and position of the diaphragm.

' Fig. 5 is a section on line 55 of Fig. 4 showing a diaphragm andacoustical chamber with sound deflectors.

Fig. 6 is another variation of angletube having an acoustical chamber.It shows the acoustical chamber with holes around the edge for entranceof sound.

Fig. 7 is a sectional view on line 1-! in Fig. 6.

Fig. 8 is a front elevation of an angletube showing an adjusting devicefor changing the sound characteristics of the acoustical chamber.

Fig. 9 is a cross section on line 9-9 of Fig. 8 showing an acousticalchamber which can be varied in shape and size to respond to variousvoice characteristics.

Fig. 10 is a rear elevation of the angletube with adjustable chambershown in Figs. 8 and 9.

Corresponding and like parts are referred to in all the views by likereference characters.

A diaphragm when transmitting speech does not resonate at one frequencybut must vibrate in therange of frequencies corresponding to the voicerange. The kinetic energy must be overcome at each cycle and since thepower available in the voice is low, the kinetic energy of the diaphragmmust be low. Therefore the diaphragm must be as light in weight aspossible. For use in gas masks the diaphragm must be mechanically strongand of a material to prevent the passage of gases.

In accordance with this invention the diaphragm is formed. of aplurality of separate plies of material secured together only at theirperipheries. Diaphragms made of cellulose derivative such as Cellophane,cellulose nitrate, or cellulose acetate, have been successfully used,

with two to five plies. Preferably four plies of cellulose acetate areused, each ply about one thousandth of an inch thick, as this assembly,afiords mechanical strength, impermeability to gases, resistance todeterioration, and vibration range to accommodate the human voice. Asufficient number of plies must be used to prevent chatter.

Voice diaphragms of individual plies secured only at their edges have avery small energy loss since the separate plies may vibrateindividually. A diaphragm made in this way has no undesirable resonancesince the separate lamina dampen the adjacent lamina.

Gas mask facepieces are usually formed of flexible material to conformclosely to the wearer's face. In order to avoid a plurality ofconnections to the facepiece, it is common practice to provide one rigidmember formed of metal, which is connected to the facepiece and by whichthe air enters and leaves the facepiece. This member, which also servesto hold the facepiece in shape and prevents collapsing due ininhalation, is known in the trade as an angle tube and is so designatedherein.

Referring to the drawings, the plied diaphragms H formed of a pluralityof plies of cellulose derivative is secured at its periphery against agasket 12. From Figure 1 it will be noted that an angle tube [4 issuitably secured in a gas-tight manner to the flexible facepiece [5, hasan undercut annular flange l6 against which gasket [2 is pressed.Diaphragm l I and gasket l2 are secured in place by a crimped rim ll ofthe metal acoustical box i8. Acoustical box i8 is a cup-shaped memberwith its rim progressively decreasing in depth from (the upper to the,lower portion, as seen in Figure 1. The bottom of box 18 has a pluralityof openings i9 arranged adjacent the upper portion and in front of thewearers mouth.

The gasket I2 engages against a beveled surface on flange IS, thearrangement being such that as the rim i1 is crimped in place andas'pressureis applied to diaphragm l I the gasketi 2 is displacedoutwardly to thus evenly stretch the diaphragm. Since there is nottwisting action in stretchin the diaphragm, there is no tendency towrinkleor break the thin diaphragm.

A rubber outlet valve 2! may be secured to an outlet nipple 22 on theangle tube Hi, and an inlet *hose to inlet nipple-38. It has been foundthat the sizeand shape of the acoustical chamber ior-m'ed by a box l8aiiects the sound transmitted through the diaphragm, and the shape andsize ofthe chamber varies for different voices. For

average voices, the back or bottom of chamber 18 should be placed at anangle of to the diaphragm ll.

Voice transmission may be further improved 'by'bafiles within theacoustical chamber. As seen in Figs; 1,4 and 5, a baifie 23 having-acurved upper'edge to engage the acoustical box extends downwardly'-at anangle of about 42 to the base orback 48 of the'box. I Two side bailles28 of sub- -stantial1y triangular shape extend from bafiie 23-downwardly atabout 65 to baifie 23. Bafiles 23 'and idjjustclear'diaphragmil to allow free vibration thereof.

The openings l9 andbafiles 23 and24 concentratethe voice sound waves tothe center of the diaphragm, thus increasing the efiiciency of soundtransmission.

In Figs. Sand '1 is'shown another shape of acoustical chamber. In thisform the back 25 of ;the acoustical chamber is in the shape of a cone,with the inner point out of engagement with diaphragm H. The side of thecone makes an angle of about 15 to the diaphragm. Sound enters thechamber through openings 26 in the cone.

Thisfchamber is also crimped to the angle tube [to secure the diaphragmin place, as previously described, the acoustical chamber being on theinside of the facepiece.

since th type of voice andthe interior cavity ofthe iacepiece affect'thesound transmitted by --sui-tably secured to a metal cup 28 which in turnsecures the'diaphragm ii to the angle tube. By

-m'oving the back 21 in or out, the size and shape of the acousticalchamber may be varied to suit 'the-voice of the wearer. In theopen'extended position of the back, the acoustical chamber will foestfita tenor voice, whereas in the depressed position the chamber willbest fit a bass voice.

"Resilient back 21 has a series of holes 29 around its periphery throughwhich sound enters the chamber.

The resilient back 21 may be adjusted by a thumb, screwtf threaded to astrap 32 on the 'jangIe'tube; the inner endoi the thumb screw arrangedto press the flexible facepiece'material l5 4 against a bell crank 33.Crank 33 is pivoted at 34 to the angle tube, and its inner end engagesthe resilient back 21. Thumb screw 3| may have a numbered dial forcooperation with a mark 35 on the strap 32.

Two angl tubes with diaphragms and acoustical chambers may be mounted in",the; cheek portions of the facepiece as seen in Fig. 3. -One angletube 36 may have its acoustical chamber arranged to respond moreeificiently to a tenor voice, the

. ,other. angle tube 31 to a bass voice, thus giving a widerrange ofvoice transmission without re- ;sorting' to ;an adjustable acousticalchamber.

The optimum size and shape of the chambers for a certainshape offacepiece may be determined by -talking tests or by impressing knownsound waves within the iacepiece at various frequencies and measuringthesound transmitted through the diaphragms.

It will be understood that the invention is not limited tothe precisedetails herein shown and described by .way of illustration, since manychanges and variations may' be made therein by those skilled in the artwithout departing from the-spiritoi the invention nor exceeding thescope of the appended claims.

' I claim: 7

1. A voice transmitting gas mask comprising a iacepiecaand a diaphragmtherein in voice transmitting relation to the mouth of the wearer, saiddiaphragm formed of a plurality of layers of thin gas-resistantmaterial'secured together only at men edges and stretched taut.

' 2. The invention as defined in claim 1 wherein said diaphragm isformed of a plurality of layers of a cellulose derivative.

3. The invention as defined in claim 1 wherein said diaphragm is formedof a plurality of layers -cf cellulose acetate.

4. In a voice transmitting mask, a sound box having a perforated bottom,an angle tube, a diaphragm formed of a plurality of plies of cellulosederivative positioned between said sound box and angle tube, and meansto secure said sound box and angle tube together and simultaneouslystretch said diaphragm, said plurality of plies beingsecured only attheir edges.

5. A voice transmitting gas mask comprising a 'fa'cepiece, an annularcup-shaped angle tube 'secured therein, a voice-transmitting diaphragmclosing said angle tube, said' diaphragm being formed of a-pluralityofseparate layers of-material secured together only at their edges, saidangle tube having an annular lip having adiaphragm engaging surface atan angle to the :plane ofwthe diaphragm, saiddiaphragm-being pressed'againstsaid surface to thereby stretch the diaphragm.

6:, Th invention as'defined in claim- 5 wherein asound box is secured tosaid angle tubewithin the facepiece to concentrate sound waves on thediaphragm.

5'7. Acvoice transmitting gas mask comprising a facepiece, an angle tubesecured therein, a diaiphragmiormed of a plurality of plies of gas-."impermeable material, means to secure said' diaphragm across saidangle tube, said -means securingsaid diaphragm only around its edge, anda sound amplifying box on theinside'of said facepie'ce forming a chamberhaving a perforated bottom, said bottom being positioned at; an angle tothe diaphragm.

i 18 The invention asdefined inclaim 'l wherein Said am i s b Lh S btber inslorin toward" the center of the diaphragmwhereby voice waves areconcentrated toward said center.

9. The invention as defined in claim 7, wherein cooperating means areprovided on the angle tube and amplifying box to secure these memberstogether, said cooperating means also securing and stretching saiddiaphragm.

10. The invention as defined in claim 7, wherein said diaphragm isformed of three to five plies of cellulose acetate.

11. A voice transmitting gas mask comprising a facepiece, an angle tubesecured therein, a diaphragm formed of a plurality of plies ofgasimpermeable material, means to secure said diaphragm only around itsedge, and a sound amplifying box on the inside of said facepiece, saidbox having closed side walls and a perforated bottom, said bottom beingreadily adjustable toward and from the diaphragm to thereby adjust thesize of the sound box to the voice.

12. A voice-transmitting assembly for gas masks, comprising incombination, an angle tube, a sound amplifying box joined to the angletube at one side of the latter, coacting means on the angle tube and onthe sound amplifying box providing a joint therebetween, a diaphragmsecured within the confines of said joint with the marginal edge only ofsaid diaphragm being clamped between the coacting means on the angletube and sound amplifying box, and said sound amplifying box having awall adapted to be flexed toward and away from said diaphragm, and meansaccessable at the side opposite the sound amplifying box for adjustablyflexing said wall.

ARMAND V. MOTSINGER.

of the angle tube

